Volume of Frustum (Truncated Cone)

If there is a frustum with base radii of 1.75 and 1.25 inches, and a height of 6 inches, what is the volume? I tried to use the V=|(b1*h1)/3-(b2*h2)/3)| from the Wikipedia page, but h2 is unknown. I get an answer of 42.41 in^3. Is this correct?